Surfactants have a wide variety of functions such as emulsification, dispersion, cleaning, wetting and foaming. Using these various functions, they have been employed for many years in numerous fields led by fibers and including paper, rubber, plastics, metals, paints, pigments, civil engineering and construction. Especially in recent years, there is an increasingly active move toward providing merchandise, which make use of surfactants, with higher performance. Keeping in step with this move, attentions have also been drawn to drawbacks which surfactants are associated with.
For example, surfactants are contained in products such as paints, printing inks and adhesives, because they are considered to be indispensable upon production or from the standpoint of stabilization of the products and working convenience. Upon actually using such surfactants-containing products in work such as coating, printing, adhesion or bonding, however, the surfactants are fundamentally unnecessary and in many instances, rather deteriorate properties such as waterproofness and oil resistance of coatings, printed surfaces, adhesive films and the like.
Emulsifiers for emulsion polymerization, which are used upon producing polymers by emulsion polymerization, are known not only to take part in polymerization-initiating reactions and polymer-forming reactions but also to affect the mechanical stability, chemical stability, freezing stability, storage stability and the like of the resulting emulsions. Further, they are also known to give significant effects on physical properties of the emulsions, such as particle size, viscosity and foaming potential and, when formed into films, physical properties of the films, such as waterproofness, weatherability, adhesion and heat resistance. As problems in such emulsion polymerization, it has been pointed out that the emulsion-polymerized emulsions are highly foamed due to the emulsifiers contained therein and that physical properties of films, such as adhesion, waterproofness, weatherability and heat resistance, are lowered. In polymers produced by suspension polymerization, similar problems caused by the dispersants for the suspension polymerization have also been pointed out.
These problems can be attributed to the surfactants still remaining in free forms in the polymers. As a method for lowering the contents of such free surfactants, surfactants which react with polymers during polymerization or molding or other forming and do not remain in free forms in the polymers, that is, so-called reactive surfactants which may also be called “polymerizable surfactants” have been developed.
Concerning reactive surfactants, many structures have been proposed. Paying attention to their hydrophobic groups, examples can include sulfosuccinate esters containing hydrocarbon groups disclosed in JP 49-46291 B; alkoxylates of allyl- or propenyl-containing, hydrocarbyl-substituted phenols, disclosed in JP 62-100502 A, JP 63-23725 A, JP 4-50202 A and JP 4-50204 A; alkoxylates of hydrocarbyl- or acyl-containing glycerin derivatives, disclosed in JP 62-104802 A; formaldehyde-crosslinked, (substituted) phenol derivatives disclosed in JP 62-11534 A; and as hydrophobic groups, alkyl groups derived from an α-olefin oxide, disclosed in JP 63-319035 A and JP 4-50204 A. Incidentally, the term “hydrocarbon or hydrocarbyl group” as used in the above-described conventional art includes alkyl groups, alkenyl groups, aryl groups, and the like.
Among these reactive surfactants, those containing one or more phenyl ether groups as hydrophobic groups have found wide-spread utility for their excellent properties such as emulsifying property, dispersing property, and polymerization-stabilizing property.
In recent years, however, a concern has arisen about a potential problem that nonyl phenol may show false hormone effects on organisms to disrupt the endocrine system, that is, the so-called endocrine problem has arisen, so that research have also been conducted in efforts to provide replacements for reactive surfactants containing one or more phenyl ether groups. However, reactive surfactants containing one or more hydrophobic groups other than phenyl ether groups, for example, general alkyl groups, alkenyl groups or the like are accompanied by a drawback in that they are inferior in performance to the reactive surfactants containing one or more phenyl ether groups.
An object of the present invention is, therefore, to solve the above-described conventional problems, and to provide a surfactant which does not contain any phenyl ether group considered to give considerable effects on the environment, such as nonylphenyl group, and has performance comparable with the reactive surfactants containing one or more phenyl ether groups.